1. Field of the Invention
The present invention is directed generally to printed circuit boards and related connectors, and more particularly, to a system and method for providing distribution of three-phase alternating current ("AC") on a printed circuit board.
2. Description of the Prior Art
Companies that develop electronic equipment for three-phase AC operation face the challenge of designing a power distribution system that meets the requirements of organizations, such as Underwriters Laboratories Inc. ("UL") and the Canadian Standards Association ("CSA"). Also, in a global economy, equipment often needs to be compatible with both the 120V three-phase AC environment found in the United States and Japan and the 220V three-phase AC environment found in other countries, particularly in Europe. The design task is even more complicated when three-phase alternating current must be distributed on a printed circuit board where space on the board is often limited.
FIG. 1 shows a prior art system 10 for distributing three-phase alternating current on a printed circuit board 12. The system 10 comprises a connector 14 having a plurality of pins (e.g., pin 16) and a corresponding plurality of traces 20-28, each of which is electrically connected to one or more of the respective pins via a solder pad (e.g., solder pad 18). As is common in the prior art, each of the pins connected to traces 22, 24, and 26 are defined to carry one of the three phases of the alternating current. Three of the other pins are collectively connected to a single trace 20 defined as a neutral. Trace 28 and its corresponding pin are undefined in this example. As is common with this type of system, the pins of the connector 14 are arranged substantially in a line and are spaced equidistantly from each other, i.e., the spacing, S, between the different solder pads (and associated traces) on the printed circuit board 12 is uniform.
With respect to the three-phase AC distribution system illustrated in FIG. 1, regulatory agencies and other organizations have set certain minimum safety requirements for the spacing, S, between adjacent traces that carry the different phases for a three-phase AC distribution. Unfortunately, the minimum spacing requirements are different in the United States and Japan than the requirements in Europe, mainly as a result of the different operating voltages in those regions--120 V in the United States and Japan, 220V in Europe. Specifically, for 120V three-phase AC distribution, two traces that carry respective phases of the AC must be spaced apart at least 2.5 millimeters. For 220V three-phase AC distribution, the spacing must be a minimum of 3.2-4.0 millimeters. A problem that arises as a result of these differences is how to design a three-phase AC distribution system for a printed circuit board that can operate in both 120V and 220V environments.
One solution to the minimum spacing problem is simply to use a larger connector designed with larger clearances for boards that will be operated in the larger voltage environment. Another solution for larger voltages is to use a separate connector for each of the different phases. Unfortunately, these solutions are disadvantageous because they require more room on the printed circuit board and a more expensive connector solution. A more preferable solution would allow a single three-phase AC distribution system to be used in both environments while optimizing distribution density and reducing cost. The present invention satisfies this need.